Iodine is a globally valuable material, which is used as: materials for daily commodities such as contrast mediums for X-ray, pharmaceutical products, anti-microorganism agent/fungicide, and the like; an industrial material for catalyst stabilizers, photographic materials, and the like; and an agricultural material for animal-feed additives, herbicides, and the like. Iodine is generally produced by purifying iodine from a mixture containing either iodine or an iodine compound. It is known that iodine can be purified from, for example, ore, brine, seaweed ash, and waste materials containing either iodine or an iodine compound. Especially, it is highly beneficial to recover valuable iodine from waste materials, in terms of cost, environment, and resource saving. As described above, various products include iodine as their raw materials, intermediates, catalysts, and the like. For example, organic compound synthesis may use iodine in the form of a simple substance or a compound. However, not all the iodine provided to the synthesis contributes to the synthesis. Some of the iodine is left unreacted, and another some of the iodine forms another compound. That is, waste materials produced through a manufacturing process contain iodine as simple iodine or as various inorganic or organic compounds. The waste materials vary in forms such as waste liquids (waste water and waste oil) and sludge. Patent Literature 1 discloses an example of a method for recovering iodine from such waste materials. The method is an iodine recovery method with combustion. In the method of Patent Literature 1, an alkali metal compound and a medium are mixed with a waste material containing iodine or an iodine compound. The mixture is combusted, and then sodium iodide or hydrogen iodide contained in the resultant gas is absorbed by an aqueous alkaline solution. Eventually, iodine is purified from the aqueous alkaline solution which has absorbed the sodium iodide or the hydrogen iodide.
Citation List
Patent Literature 1    Japanese Patent Application Publication, Tokukaihei, No. 6-157005 A (Publication Date: Jun. 3, 1994)